1. Field of the Invention
The present invention relates to a liquid eject head to eject liquid droplets from eject ports, to a cartridge as a unit comprising the liquid eject head and a liquid tank for reserving the liquid to be supplied to the liquid eject head and to an image forming apparatus, and also relates to a manufacturing method of the liquid eject head.
2. Brief Description of the Related Art
Liquid paths communicated to eject ports are formed by joining together a substrate where micro processed portions including eject energy generating elements for ejecting liquid droplets are formed with a grooved plate where grooves at corresponding positions to the eject energy generating elements and eject ports communicated to one ends of the grooves are formed. In liquid eject heads where liquid droplets are ejected from the liquid paths via eject ports, the substrate and the grooved plate have to be joined together by keeping an accurate positioning between them.
Up to now the substrate and the grooved plate for the liquid eject head are joined according to the following positioning method.
After recognizing one eject energy generating element marked beforehand among eject energy generating elements formed on the substrate, the grooved plate is placed and moved without touching it on the substrate until the marked eject energy generating element reaches a position where a marked groove or marked eject port is formed. Or a positioning stopper to which the side end of the substrate is attached, is formed at end portion of the grooved plate so that the grooved plate is placed on the substrate and moved to a position where it is pressed against the positioning stopper.
Recently in order to meet requirements for finer image forming, eject ports more densely arranged on the liquid head have been realized. For that purpose, spacing between two neighboring liquid paths and a thickness of a partition wall to divide liquid paths should be formed thinner and thinner. When the grooved plate contacting with the substrate is moved on the substrate with keeping its contacting state, there are possibilities to deform or damage the grooved plate, or to damage eject energy generating elements formed on the substrate since the substrate is not perfectly flat. Consequently, lower ends of partition walls formed on the grooved plate scratch the substrate.
Such damages or deformations may cause cross talk between two neighboring liquid paths and make predetermined accurate ejection of liquid difficult, consequently printing quality is deteriorated. When eject energy generating elements are damaged, the printing quality is also deteriorated owing to deteriorated durability of eject heads and difficulties to keep normal ejecting performance.
When micro processed portions except the eject energy generating elements arranged on the substrate are damaged or deformed, durability of the eject heads is deteriorated and it becomes difficult to keep normal ejecting operations, which leads to deteriorated printing quality.
Since the above-mentioned problems increase along with demands for eject ports with higher density, an easy and fast positioning method is required without contacting the grooved plate to the substrate which is not formed perfectly flat.
In the method disclosed in the U.S. Pat. No. 5,992,981 where a positioning method between each eject energy generating element arranged on the substrate and each corresponding nozzle formed on the grooved plate is proposed, there is also a possibility to cause damages on micro processed portion. In other words in order to avoid such possibility to cause such damages on the micro processed portions, the height of walls forming liquid paths should be set larger than a sum of a height of protrusions formed outside the aligned row of eject energy generating element on the substrate and a height of walls arranged outside the aligned row liquid paths on the grooved plate for forming engaging recessed portions to engage the above-mentioned protrusions.
In some case, an external force is required in order to keep the substrate having the above-mentioned energy generating elements and the grooved plate having liquid paths at the positioning state in accordance with a geometry of the above-mentioned substrate. However, portions of the grooved plate accepting protrusions are deformed by the above-mentioned applied force, which causes friction when the grooved plate is moved on the substrate for the positioning. Consequently, requirements for enhancing strength around the protrusion and for excessive higher force to move the grooved plate, may result in deteriorated positioning accuracy.
A first objective of the present invention is to provide the liquid eject head manufactured by precise positioning and joining the substrate against the grooved plate without causing any damage or deformation on the eject energy generating elements on the substrate and partition walls on the grooved plate.
A second objective of the present invention is to provide a cartridge where the above-mentioned liquid eject head and a liquid tank to reserve ink for supplying to the liquid head are combined as a unit.
A third objective of the present invention is to provide an image forming apparatus where a device for attaching the above-mentioned cartridge is arranged for forming image on a printing medium.
A fourth objective of the present invention is to provide a manufacturing method of the above-mentioned liquid eject head.
A first embodiment of the liquid eject head to attain the first objective of the present invention comprises: the substrate having a plurality of eject energy generating elements for ejecting liquid droplets, a plurality of micro processed portions including eject energy generating elements and a first surface arranged the plurality of micro processed portions thereon, and the grooved plate having a plurality of eject ports for ejecting liquid droplets, a plurality of grooves communicating to a plurality of respective eject ports for forming liquid paths and a second surface arranged the plurality of grooves thereon, wherein; the first surface and second surface are fitted together so as to keep a state where respective eject energy generating elements face against corresponding grooves, the substrate has at least two protrusions, a width of the protrusion in an arranged direction of liquid paths being set larger than the width of the liquid path and a height of the protrusion from the first surface being set higher than a height of micro processed portion, and the grooved plate has engaging recessed portions for positioning the grooved plate against the substrate by engaging protrusions with engaging recessed portions, and; a summed up height comprising; a height of the wall of the engaging recessed portion from a ceiling of the liquid path and a height of the protrusion is set larger than a height of partition walls parting liquid paths from the ceiling of the liquid path.
In this embodiment protrusions may formed outside of the arranged row of eject energy generating elements. Or an engaging recessed portion is formed on opposite side against grooves so as to communicate to a common liquid chamber and so as to function partly as the engaging recessed portion to the protrusion.
Upper ends of the protrusions may be formed as flat plane parallel to the surface of the substrate.
The eject energy generating element may an electro-thermal energy conversion element for generating thermal energy to cause a film boiling in the liquid for ejecting liquid from the eject port.
A second embodiment of the cartridge to attain the second objective of the present invention equipped with a liquid eject head which comprises: the substrate having a plurality of eject energy generating elements for ejecting liquid droplets, a plurality of micro processed portions including eject energy generating elements and a first surface arranged the plurality of micro processed portions thereon, and the grooved plate having a plurality of eject ports for ejecting liquid droplets, a plurality of grooves communicating to a plurality of respective eject ports for forming liquid paths and a second surface arranged the plurality of grooves thereon, wherein; the first surface and second surface are fitted together so as to keep a state where respective eject energy generating elements face against corresponding grooves, the substrate has at least two protrusions, a width the protrusion in an arranged direction of liquid paths being set larger than the width of the liquid path and a height of the protrusion from the first surface being set higher than a height of micro processed portions, and the grooved plate has engaging recessed portions for positioning the grooved plate against said substrate by engaging protrusions with engaging recessed portions, and; a summed up height comprising; a height of the wall of the engaging recessed portion from a ceiling of the liquid path and the height of the protrusion is set larger than a height of partition walls parting liquid paths from the ceiling of the liquid path.
In the cartridge according to this embodiment, the liquid tank may be demountably mounted to the cartridge.
The liquid may be a treatment liquid to adjust printing quality of the ink and/or ejected ink on the printing medium.
A third embodiment of the image forming apparatus to attain the first objective of the present invention having the device for attaching the liquid eject head which comprises: the substrate having a plurality of eject energy generating elements for ejecting liquid droplets, a plurality of micro processed portions including eject energy generating elements and a first surface arranged the plurality of micro processed portions thereon, and the grooved plate having a plurality of eject ports for ejecting liquid droplets, a plurality of grooves communicating to a plurality of respective eject ports for forming liquid paths and a second surface arranged the plurality of grooves thereon, wherein; the first surface and second surface are fitted together so as to keep a state where respective eject energy generating elements face against corresponding grooves, the substrate has at least two protrusions, a width of the protrusion in an arranged direction of liquid paths being set larger than the width of the liquid path and a height of the protrusion from the first surface being set higher than a height of micro processed portions, and the grooved plate has engaging recessed portions for positioning the grooved plate against the substrate by engaging protrusions with engaging recessed portions, and; a summed up height comprising; a height of the wall of the engaging recessed portion from the ceiling of the liquid path and a height of the protrusion is set larger than a height of partition walls parting liquid paths from the ceiling of the liquid path.
In the image forming apparatus according to the third embodiment the device for attaching the liquid eject head may be a carriage which is capable of scanning and moving across a feeding direction of the printing medium onto which the liquid is ejected from the liquid eject head. In this case the liquid eject head may be demounted to the carriage by a demounting means.
A fourth embodiment of the manufacturing method of the liquid head to attain the fourth objective of the present invention wherein: the substrate having a plurality of eject energy generating elements for ejecting liquid droplets, a plurality of micro processed portions including eject energy generating elements and a first surface arranged the plurality of micro processed portions thereon and the grooved plate having a plurality of eject ports for ejecting liquid droplets, a plurality of grooves communicating to a plurality of respective eject ports for forming liquid paths and a second surface arranged the plurality of grooves are formed are arranged, wherein; the first surface and second surface are fitted together so as to keep a state where respective eject energy generating elements face against corresponding grooves, wherein the manufacturing method of the liquid eject head comprises steps of: forming at least two protrusions having a width of the protrusion in an arranged direction of the liquid paths being set larger than the width of the liquid path and a height of the protrusion from the first surface being set higher than a height of the micro processed portions, apart from each other on the substrate, forming corresponding engaging recessed portions having a height of the wall of the engaging recessed portion from the ceiling of the liquid path, wherein; a summed up height comprising; a height of the wall of the engaging recessed portion from the ceiling of the liquid path and a height of the protrusion is set larger than a height of partition walls parting liquid paths from the ceiling of the liquid path, mounting the grooved plate on upper ends of protrusions, moving the grooved plate along upper ends of protrusions and engaging protrusions with engaging recessed portions.
In the manufacturing method of the liquid eject head according to the fourth embodiment, force to move the grooved plate is applied preferably parallel to the surface of the substrate.
Engaging protrusions to engaging recessed portions is preferably executed by gravity force caused by own weight of the grooved plate.
Other embodiment of manufacturing method of the liquid eject head to attain the fourth objective of the present invention is carried out as follows. A liquid head comprising a substrate having a plurality of eject energy generating elements for ejecting liquid droplets, a plurality of micro processed portions including eject energy generating elements and a first surface arranged the plurality of micro processed portions thereon, and a grooved plate having a plurality of eject ports for ejecting liquid droplets, a plurality of grooves communicating to a plurality of respective eject ports for forming liquid paths and a second surface arranged the plurality of grooves thereon, wherein; the first surface and second surface are fitted together so as to keep a state where respective eject energy generating elements face against corresponding grooves, wherein the manufacturing method of said liquid eject head comprises steps of; forming at least two protrusions on the substrate having a width of the protrusion in an arranged direction of eject energy generating elements is set more than a maximum offset value including its accuracy value, further forming corresponding engaging recessed portions on the grooved plate having a length larger than the width of the upper end of the protrusion and also larger than the maximum offset value including its accuracy value, mounting the grooved plate against the substrate, moving the grooved plate along upper ends of protrusions, and engaging the protrusions with the engaging recessed portions.